EPIA M600 Not Cutting It...

I have a EPIA M600 and even though I overclocked it to 733mhz it still will not play media files smoothly. It could be the fresh rate which is set at 60hz or just the video card. So what I want to know is does anyone have an suggestions? I might as well try to get the MII 12000. I'm sure with the speed it should meet and exceed my expectations.

Alternatively I could always use one of the many ATX boards I have laying around. But what I want to know is there a slim/flat atx case? Any of the M1-Atx or OPUS power supply units that can be connected to the cars battery be used on standard ATX cases?

If I was to decide to use a standard ATX MB w/ just the essentials what can I power it with? Essentials meaning, 2-3 fans, cpu, 512mb ram, video card, 1.3ghz amd cpu, wireless network card, 5.1 sound card. If there is room for some leds that would be nice too.